That way you can create your GUI once and it will look the same in every resolution.

You can do this now by script but it is ALOT of work. For every resoltion, every panel has to be placed and scaled, every panel element has to be placed and scaled. Texts have to be placed differently, using a different font for every resolution, the line breaks have to be changed, etc. It's possible but really bothersome.

This could be achieved by rendering all panels into a seperate bitmap and then scaling that bitmap to the screen resolution before overlaying it on the camera.